[Halld-physics] Reading Group Friday

[Curtis A. Meyer]

I am still not sure I understand the numbers in the Karliner/Rosner paper, but they have peak
cross sections in the ub (micro barn) range, not the nb range for J/Psi production. This is probably
when I first started hearing about this, I assumed that the rates we could observe with nb or smaller
cross sections would make this incredibly hard to pull out. If a ub cross section is real, this would
stand out pretty clearly in our data.

Curtis
---------
Curtis A. Meyer			MCS Associate Dean for Faculty and Graduate Affairs
Wean:    (412) 268-2745	Professor of Physics
Doherty: (412) 268-3090	Carnegie Mellon University
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curtis.meyer at cmu.edu	http://www.curtismeyer.com/



> On Aug 7, 2015, at 12:31 PM, Eugene Chudakov <gen at jlab.org> wrote:
> 
> There is a collection of various links concerning J/psi
> close-to-threshold photoproduction (see "meeting, talks") as well as
> the older papers:
> 
> https://userweb.jlab.org/~gen/charm/
> 
> A few numbers:
> 
> The expected gamm+p-->J/psi+p cross section at 10 GeV is about 0.1nb.
> The lowest Cornell point was about 0.5nb for <12 GeV. This led Brodsky
> to speculate that there could be some anomaly.
> 
> We do not know the gamma+p-->P-->J/psi rate, but may assume, as the
> starting point, the same ratio to non-resonance J/psi+p events as LHCB
> had for the LB spectrum.  They had about 500 events per 15MeV bin. For
> the incoming photon it would be an 80 MeV bin.
> 
> Assuming 0.1nb I estimated that one can get about 1600 events/bin in
> Hall C (based on PR12-07-006 proposal)) and 100 events in Hall B
> (based on PR12-12-001 proposal) for a 3-month run.
> 
> For GlueX at "low" intensity and the regular running (peak at 9 GeV
> and 3mm hole) it would be about 2 ev/bin. Using the 5mm hole and 5
> times more current would give about 20 ev/bin.
> 
> Eugene
> 
> 
> 
> ------------------------------------------------------
> Eugene Chudakov
> https://userweb.jlab.org/~gen/
> phone (757) 269 6959  fax (757) 269 6331
> Thomas Jefferson National Accelerator Facility
> 12000 Jefferson Ave, STE 4,
> Newport News, VA 23606 USA
> 
> On Fri, 7 Aug 2015, Richard Jones wrote:
> 
>> Matt,
>> 
>> As this paper makes clear, Reinhard's idea of looking for this state in
>> formation mode with GlueX at 10GeV is well within reach. Of course the BR
>> to J/Psi,p might be miniscule but if so then why would this be the first
>> mode in which it has been seen? My comment to Reinhard last Friday that
>> searching for ccbar baryons in GlueX would be a long shot was incorrect.
>> 
>> -Richard Jones
>> 
>> On Wed, Jul 22, 2015 at 11:11 AM, Shepherd, Matthew <mashephe at indiana.edu>
>> wrote:
>> 
>>> 
>>> Hi all,
>>> 
>>> We decided to break momentarily from the photoproduction theme to read and
>>> discuss this timely paper from LHCb on pentaquarks with hidden charm.
>>> 
>>> http://arxiv.org/abs/1507.03414
>>> 
>>> Let’s meet Friday at 3:30 in F326/7.  Focus primarily on the article
>>> itself, which is the first 15 pages.
>>> 
>>> Please bring questions and topics for discussion!
>>> 
>>> Matt
>>> 
>>> ---------------------------------------------------------------------
>>> Matthew Shepherd, Associate Professor
>>> Department of Physics, Indiana University, Swain West 265
>>> 727 East Third Street, Bloomington, IN 47405
>>> 
>>> Office Phone:  +1 812 856 5808
>>> 
>>> 
>>> _______________________________________________
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